It is widely known that easily accessible resources of fossil fuels are declining. In addition, the impact of the use of fossil fuels upon the environment has become increasingly apparent. As a result of this, it has become imperative that viable alternative energy sources are used as effectively and efficiently as possible. For example, the use of turbines to capture the power of water flow, such as tidal, river and ocean current flows is becoming a viable source of alternative energy. The turbine equipment used to capture such water flow energy typically includes a shaft driven generator connected using a drivetrain to a rotor assembly. The rotor assembly includes a plurality of rotor blades that are driven by the water flow, so as to turn an input shaft of the drivetrain. Alternative water-based power generation devices such as wave driven devices are also being considered.
In order to be economically practical, multiple power generating devices should be deployed in a suitable area. For example, a tidal turbine farm may have tens to hundreds of turbines. The turbines are preferably arranged in an array having multiple rows of multiple turbines. The turbine array could be deployed in a tidal flow area, a river flow, an ocean current, or any other suitable water current area. Although it is preferable for the turbines to be arranged in an array, geography, bathymetry and other factors may mean that a turbine farm has another arrangement.
In order that such an array of power generating devices are able to export the generated power from the array, and to receive control signals, it is necessary to provide an amount of infrastructure equipment for the array. In a simple arrangement, each power generating device can be connected directly to infrastructure located on the shore. However, such a solution results in many cables being laid, often over large distances. Offshore wind farms make use of switching, transformer and control equipment located in dry spaces above the surface of the water. For such offshore wind farms, providing the infrastructure equipment above the surface does not present any additional problems or issues, since the wind turbines themselves are, naturally, above the water.
However, water current turbines are located underwater, and are often located in water too deep to make surface breaking structures practical. In addition, since the remainder of the array would be under the water surface, it is unlikely that permission would be given for the provision of a surface breaking infrastructure unit. Even where floating wave devices are deployed, it is desirable to minimise the amount of surface breaking equipment.
Installation, maintenance and servicing of such underwater infrastructure equipment, such as switches, frequency converters, isolators, circuit breakers signal boosters, transformers, and measurement and control equipment, particularly in deep sea environments, are highly costly and time consuming procedures. Infrastructure equipment typically requires through-life inspection, maintenance and servicing. It is therefore desirable to simplify the construction and deployment of underwater infrastructure equipment, lowering capital cost and enabling inspection, servicing and maintenance of the infrastructure equipment in a relatively cost effective and efficient manner.